On "The Tonight Show" Thursday night, Jay Leno had this reaction to cyclist Lance Armstrong's much-anticipated confession that he'd used performance-enhancing drugs: "The guy’s a liar, a cheat, a hypocrite, a fraud. Where’s he going to find work? OK, besides Congress. I mean, besides Congress, there are not a lot of options."

It's a funny quip, of course – but it also happens to have more than a grain of truth to it. For public figures who have experienced humiliating falls from grace – often involving confessions of wrongdoing and tearful apologies – there may be no more forgiving profession than politics.

Just this week, former South Carolina Gov. Mark Sanford (R) – whose infamous 2009 Appalachian Trail trip turned out to be a visit to his Argentine mistress – announced he will attempt to return to Congress, where he served from 1995 to 2001, by seeking the seat vacated by now-Sen. Tim Scott (R).

“We all hope for redemption, we all hope for second chances,” Mr. Sanford told a local TV station in an interview. “Whether or not I’m granted one, time will tell. But what I would say is, it’s a fresh start in that, you know, after you have failed at something, I think you see life through a different prism. So the prism I have is maybe with a little bit greater humility and a little bit more reserve, but it is to say, ‘Well, can I take what I learned on the way up and on the way down; can I take what I learned in Congress and the governorship and apply it?’ ”

If Sanford succeeds, he'll join a long list of men who've resurrected their political careers after highly publicized (most often extramarital and usually not illegal) missteps.

To name just a few of the most prominent: There are former President Clinton (survived an affair with an intern and impeachment proceedings; is now about to receive a "father of the year" award, with approval ratings at an all-time high of 69 percent); Sen. David Vitter (R) of Louisiana (won reelection handily after overcoming a prostitution scandal); former Rep. Barney Frank (D) of Massachusetts (held a long and distinguished career in the House after it was revealed his gay lover was running an escort ring out of his house; is now a leading contender to fill an interim Senate post in Massachusetts); and former House Speaker Newt Gingrich (was a presidential hopeful in 2012 – and won the South Carolina primary – after he'd left the House admitting to infidelity and having been formally disciplined on ethics charges).

It was even reported this week that former Rep. Anthony Weiner (D) of New York (who resigned after it was revealed he'd been sending risqué pictures of himself via Twitter to women who were not his wife) has reserved the domain name AnthonyWeiner2013.com and continues to maintain office space in New York City for a possible mayoral campaign. So far, however, Mr. Weiner has not indicated any intention to run.

We confess, we're not entirely sure what to make of this phenomenon. Much has been written over the years about how the American people are unusually forgiving and, indeed, often seem to root for "second chances." Others have pointed out that, in this age of 24/7 news, the spotlight's glare can be intense and cruel when a scandal breaks, but it also moves on quickly – and the public can have a relatively short memory.

Either way, the ease with which many have been able to mount political comebacks after a scandal is pretty striking when you consider that elective office, unlike other careers, requires a literal vote of confidence from vast numbers of constituents.

There do seem to be some rules, though, for mounting a successful political comeback. As a prerequisite, you must own up to what you did and show genuine remorse. But, paradoxically, you also can't seem too overcome by shame: You need to indicate that you've moved on and that you expect others to, as well.

The nature of the scandal also clearly makes a difference. Scandals involving homosexual activity have proved far more difficult to overcome, particularly for Republicans (see former Idaho Sen. Larry Craig and former Florida Rep. Mark Foley, among others). Former California Rep. Gary Condit (D) was cleared in the death of intern Chandra Levy, for which another man was convicted – but the murder of a young woman, with whom he'd apparently had an inappropriate relationship, still proved impossible for him to get beyond.

And it is certainly harder – though not impossible – for elected officials to get past illegal activity (on the local level, former D.C. Mayor Marion Barry – who went to jail on drug charges, was subsequently reelected as mayor, and now sits on the city council – comes to mind).

Finally, there do seem to be some "moral decency" limits as to what the public is willing to forgive. Former North Carolina Sen. John Edwards (D) may be off the hook, legally, for his affair with a videographer working for his presidential campaign. But the deep public sympathy for his late wife, Elizabeth, who was fighting cancer while the extramarital affair was taking place, seems likely to prohibit any sort of political comeback for him.